feat: rebuild pet app and backend around core care flows

pets-be/cmd/dbinit/main.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"regexp"
+
+	"gorm.io/driver/postgres"
+	"gorm.io/gorm"
+
+	"github.com/sundynix/pets-be/internal/config"
+)
+
+var databaseName = regexp.MustCompile(`^[a-zA-Z0-9_-]+$`)
+
+// dbinit creates the configured PostgreSQL database once. It does not change other databases.
+func main() {
+	cfg, err := config.Load()
+	if err != nil {
+		log.Fatal(err)
+	}
+	name := cfg.Postgres.Database
+	if !databaseName.MatchString(name) {
+		log.Fatal("invalid database name")
+	}
+	maintenance := cfg.Postgres
+	maintenance.Database = "postgres"
+	db, err := gorm.Open(postgres.Open(maintenance.DSN()), &gorm.Config{})
+	if err != nil {
+		log.Fatal(err)
+	}
+	var count int64
+	if err := db.Raw("SELECT count(*) FROM pg_database WHERE datname = ?", name).Scan(&count).Error; err != nil {
+		log.Fatal(err)
+	}
+	if count > 0 {
+		log.Printf("database %s already exists", name)
+		return
+	}
+	if err := db.Exec(fmt.Sprintf("CREATE DATABASE \"%s\"", name)).Error; err != nil {
+		log.Fatal(err)
+	}
+	log.Printf("created database %s", name)
+}